Wave receivers in Antarctic Automatic Geophysical Observatories (AGOs) measure spectral features of low-frequency impulsive auroral hiss emissions which cannot be observed at northern hemisphere sites or near manned Antarctic stations due to man-made interference. From observations at AGO-P1 (~80¿ invariant latitude) we distinguish two spectral types of LF impulsive auroral hiss: normal events, in which the power spectral density is a decreasing function of frequency throughout the LF band, presumably peaking in the VLF band below the frequency range of the LF/MF/HF receiver; and LF cutoff events, for which the power spectral density peaks in the LF band with little or no power at VLF. Out of a large sample of impulsive auroral hiss events observed at AGO-P1, 64% are the normal type, 14% are the LF-cutoff type, and 22% are a mixture of both. A hiss propagation model similar to that of Makita [1979> was used to evaluate approximately whether the observed occurrence statistics of LF cutoff auroral hiss are consistent with previous models of auroral hiss generation and propagation. The results indicate that LF cutoff auroral hiss can be explained by propagation effects and suggest that the observed LF cutoff occurrence statistics are consistent with LF impulsive auroral hiss originating at or ducted to altitudes of 2000--5000 km. ¿ 1998 American Geophysical Union